Email: [email protected]

Status: 4th Year Graduate Student

Undergraduate Institution: Rensselaer Polytechnic Institute

Ph.D. Thesis Research:

Semicrystalline polymers which exhibit ductility are desirable in many commercial applications due to their resistance to brittle fracture, resulting in breaking strains orders of magnitude higher than brittle polymers. Tie molecules, which quite literally tie polymer crystallites together through the amorphous phase, are widely recognized as the key contributor to polymer ductility. However, because it is impossible to directly measure the concentration of tie molecules in any given polymer, the quantities which influence tie molecule formation have proven elusive to polymer scientists. This is not to say that there have not been attempts to predict tie molecule formation. For example, over the past 30 years, the Huang and Brown model has been the dominant way of not only predicting tie molecule formation, but thinking about them as a system. While the ideas foundational to the Huang and Brown model appear sound, more recent research of linear polyethylenes (LPEs) has revealed that they are inadequate at accurately predicting whether or not a polymer will exhibit ductility, suggesting that there are other morphological factors which influence tie molecule formation that the Huang and Brown model ignores.

My research seeks to develop a new design rule for polymer ductility and tie molecule formation by synthesizing, hydrogenating, and characterizing copolymers of norbornene and hexylnorbornene. Polynorbornene, when hydrogenated, is highly crystalline while each hexylnorbornene mer is universally excluded from the crystallites. Through the synthesis of norbornene-hexylnorbornene random copolymers over a wide range of molecular weights and compositions, it should be possible to decouple the relationship between crystallinity and domain spacing while simultaneously quantifying their effects on polymer ductility. The end goal of my research will be to develop a quantitative design rule for polymer ductility that should be able to accurately predict whether any one polymer is brittle or ductile based on said polymer’s properties. Ideally, this design rule can be applied to a wide variety of projects, but one that is particularly noteworthy is using it to tune the ductility of novel multiblock copolymers with superior low-strain mechanical properties (e.g. yield stress) to their homopolymer counterparts.